1. Field of Invention
The present invention relates to a fiber optic sensor cable and a security sensor system. More particularly, the present invention relates to a security sensor cable having both optical sensing fiber, as well as power cables, within a secure cable jacket.
2. Discussion of the Prior Art
In the field of security sensor systems, outdoor sensors face challenges not found in indoor security situations. Environmental conditions, such as temperature extremes, rain, snow, animals, blowing debris, seismic effects, terrain and traffic, must all be taken into account. When functioning under these adverse conditions, the system must continue to maintain a high probability of detection while minimizing false alarms (alarms with unknown causes) and nuisance alarms (environment-related alarms), both of which may compromise and reduce the performance of the security system.
Fence and wall-associated sensors are above-ground detection sensors that are attached to an existing fence or wall. They detect intrusion when an intruder disturbs the detection field, or when strain or vibration due to cutting or climbing on a metal fabric fence triggers an alarm. INTELLIFIBER™ is a fiber-optic based fence-disturbance sensor for outdoor perimeter security applications from Senstar-Stellar Corp., of Carp, Ontario, Canada. This prior art fiber optic sensor can detect intruders cutting, climbing, or lifting fence fabric, and it provides protection circuitry against electromagnetic interference, radio frequency interference, and lightning. The system includes a programmable microprocessor that processes signals based on the changes in optical parameters generated as a result of disturbances in proximity to the fiber optic sensor cable. The microprocessor allows the user to calibrate and set operating parameters for specific zones/environments. Alarm processing optimizes detection and minimizes nuisance alarms from wind, rain, snow, fog, animals, debris, seismic activity, and the like.
There are various applications of INTELLIFIBER™ and similar fiber optic based security sensor systems. For example, one possible application is as an intrusion or disturbance detection system for communication centers. As security and disturbance detection systems at communication centers are crucial and must have a high probability of detection, certain environmental characteristics specific to the communication centers require that the system be uniquely calibrated to optimize detection. Due to the intense electromagnetic field environment that exists at these communications centers, security systems must also be able to operate without interference and also must avoid interfering with the on-site communication equipment. If the disturbance detection system were operating near a power station, similar environmental characteristics would be a consideration.
FIG. 1, in the Drawings, is a block diagram of a security sensor system 1 of the prior art. The security sensor system 1 includes a first fiber optic sensor cable 2 and a second fiber optic sensor cable 3. Both cables 2 and 3 are shown in a loop back configuration. Each cable 2 and 3 is connected, at both end of the loops, to a first processing unit 4 and a second processing unit 5, respectively. Each of these processors may be connected to a central processing system (not shown). As such, each processing unit 4, 5 receives its power supply independent of the other processing units, and furthermore data signals are not transmitted between, or routed through, the processing units 4, 5. The prior art, for example, does not conceive of a first processing unit 4 providing power to the second processing unit 5 by utilizing a power cable coupled to both processing units 4 and 5, where the power cables and sensor cables form a single cable unit. Rather, in the prior art, the power cables would be run in parallel with the sensor cables but not coupled to the sensor cables.
In addition, a security sensor system must have intelligent processing means in order to optimize detection and minimize nuisance alarms, as well as being physically robust. The security system, and more particularly the fiber optic sensor cable, must be protected from adverse environmental conditions. Furthermore, the security system requires power conductor cables to provide power to the signal generation, detection, and data signal processing at the processing means of the security system. Accordingly, both the fiber optic sensor cables and the power conductor cables require protective layers that do not interfere with the disturbance detection function.
The Arroyo patent, U.S. Pat. No. 5,913,003, discloses a composite fiber optic cable having at least one optical fiber and at least one electrical power cable. Arroyo teaches that the power cables extend alongside a core containing the fiber optic cables. Arroyo requires that a strength jacket surround the core between the power cables and the fiber optic cables. The power cables and the fiber optic cables are both protected by an outer jacket. While Arroyo does teach distribution cables intended for use with remote terminals and an optical network unit, a security sensor system is not shown or suggested by Arroyo. Furthermore, Arroyo does not provide a primary jacket and a secondary jacket for the fiber optic cables and the power cables respectively.
The Keller patent, U.S. Pat. No. 6,169,834, discloses a slotted composite cable having a housing which encases a ribbon slot for optical fibers and a tubular slot for power cables, such as copper pairs. Keller teaches that the copper pairs provide central strength to the composite cable and effectively protect the optical fiber slots. Keller further teaches a composite cable for the purposes of communicating data, voice and power signals, however, there is no discussion of distributed networks or sensor systems. Still further, the discussion of the Keller prior art does not teach utilizing the cable composite for the purposes of security sensor systems.
The present invention seeks to provide a secure overjacket structure that is useful in preventing intruder tampering with the power cables. The present invention further seeks to provide a secure overjacket structure that protects both the fiber optic cabling and the power conductor cables, and ensures secure data transmission within a security sensor system. It is further advantageous to have both the fiber optic cabling and the power cables within a single protective jacket to eliminate the installation of both cables separately.